Demi Lovato in rehab

Disney princess Demi Lovato quit the Jonas Brothers tour and checked into rehab for what her reps are calling "emotional and physical issues."

A statement from her reps says Demi Lovato "left her tour early this weekend in order to seek medical treatment for emotional and physical issues she has dealt with for some time."

"Demi has decided to take personal responsibility for her actions...she is doing just that. Demi and her family ask that the media please respect their privacy during this difficult time," the statement continued.

Sources tell TMZ that the 18-year-old star is not being treated for any substance abuse problems. Those same sources say Lovato is a cutter and has an eating disorder, and that she got into a catfight with one of her female backup dancers recently.

Perhaps the pressures of fame plus Lovato's split with longtime boyfriend Joe Jonas on May 2010 all became too much.